1. Field of the Invention
This invention relates to communication through a channel, and more specifically to correction of distortion introduced into wideband signals communicated through a channel.
2. Description of Related Art
Analog or digital information typically is transmitted from one place to another through a channel. A channel is a general term referring to the medium through which a signal is transmitted. The channel may be a radio transmission, local area network transmission, telephone transmission, etc. In each case, the received signal differs from the transmitted signal due to the effects of the transmission through the channel. A transmitted signal may travel by a first path directly from a transmit unit to a receive unit having a distance d.sub.1. This is the most desirable transmission path, however there are cases when the transmitted signal travels by alternate paths. The signal may, in the case of a radio channel, be reflected from an obstacle, such as a mountain, to the receive unit over a second path having a distance d.sub.2, being longer than d.sub.1. The transmission over the second path arrives at the receive unit slightly later as an `echo`. There may also be several paths and echoes. The condition of several signals arriving at the receive unit if referred to as `multipath propagation`.
Since signals arriving via different paths travel different distances, the phases detected at the receive unit are different. This causes significant problems in decoding signals with several signals received approximately at the same time with unknown phases.
In most communication systems it is desirable to have knowledge of this channel information, known as channel state information (CSI) at any instant of time in order to properly decode the transmitted information.
Currently there is a need for a simplified method of correcting channel induced phase distortion in wideband signals.